In manufacturing of organic electronics, inkjet printing as an alternative technique for depositing materials is becoming increasingly important. Aside to the ink formulations challenges, improving the resolution of the printed patterns is a major goal. In this study we will discuss a newly developed technique to selectively modify the substrate surface energy using plasma treatment as a means to achieve this goal. First, we look at the effects of the μPlasma treatment on the surface energy for a selection of plastic films. Second, we investigated the effects of the μPlasma treatment on the wetting behaviour of inkjet printed droplets to determine the resolution of the μPlasma printing technique. We found that the surface energy for all tested films increased significantly reaching a maximum after 3-5 repetitions. Subsequently the surface energy decreased in the following 8-10 days after treatment, finally stabilizing at a surface energy roughly halfway between the surface energy of the untreated film and the maximum obtained surface energy. When μPlasma printing lines, an improved wetting abillity of inkjet printed materials on the plasma treated areas was found. The minimal achieved μPlasma printed line was found to be 1 mm wide. For future application it is important to increase the resolution of the plasma print process. This is crucial for combining plasma treatment with inkjet print technology as a means to obtain higher print resolutions.
DOCUMENT
In this article we investigate the change in wetting behavior of inkjet printed materials on either hydrophilic or hydrophobic plasma treated patterns, to determine the minimum obtainable track width using selective patterned μPlasma printing. For Hexamethyl-Disiloxane (HMDSO)/N2 plasma, a decrease in surface energy of approx. 44 mN/m was measured. This resulted in a change in contact angle for water from <10 up to 105 degrees, and from 32 up to 46 degrees for Diethyleneglycol-Dimethaclylate (DEGDMA). For both the nitrogen, air and HMDSO/N2 plasma single pixel wide track widths of approx. 320 μm were measured at a plasma print height of 50 μm. Combining hydrophilic pretreatment of the glass substrate, by UV/Ozone or air μPlasma printing, with hydrophobic HMDSO/N2 plasma, the smallest hydrophilic area found was in the order of 300 μm as well.
DOCUMENT
Inkjet printing is a rapidly growing technology for depositing functional materials in the production of organic electronics. Challenges lie among others in the printing of high resolution patterns with high aspect ratio of functional materials to obtain the needed functionality like e.g. conductivity. μPlasma printing is a technology which combines atmospheric plasma treatment with the versatility of digital on demand printing technology to selectively change the wetting behaviour of materials. In earlier research it was shown that with μPlasma printing it is possible to selectively improve the wetting behaviour of functional inks on polymer substrates using atmospheric air plasma. In this investigation we show it is possible to selectively change the substrate wetting behaviour using combinations of different plasmas and patterned printing. For air and nitrogen plasmas, increased wetting of printed materials could be achieved on both polycarbonate and glass substrates. A minimal track width of 320 μm for a 200 μm wide plasma needle was achieved. A combination of N2 with HMDSO plasma increases the contact angle for water up from <100 to 1050 and from 320 to 460 for DEGDMA making the substrate more hydrophobic. Furthermore using N2-plasma in combination with a N2/HMDSO plasma, hydrophobic tracks could be printed with similar minimal track width. Combining both N2 -plasma and N2/HMDSO plasma treatments show promising results to further decrease the track width to even smaller values.
DOCUMENT
Fontys University of Applied Science’s Institute of Engineering, and the Dutch Institute for Fundamental Energy Research (DIFFER) are proposing to set up a professorship to develop novel sensors for fusion reactors. Sensors are a critical component to control and optimise the unstable plasma of Tokamak reactors. However, sensor systems are particularly challenging in fusion-plasma facing components, such as the divertor. The extreme conditions make it impossible to directly incorporate sensors. Furthermore, in advanced reactor concepts, such as DEMO, access to the plasma via ports will be extremely limited. Therefore, indirect or non-contact sensing modalities must be employed. The research group Distributed Sensor Systems (DSS) will develop microwave sensor systems for characterising the plasma in a tokamak’s divertor. DSS will take advantage of recent rapid developments in high frequency integrated circuits, found, for instance, in automotive radar systems, to develop digital reflectometers. Access through the divertor wall will be achieved via surface waveguide structures. The waveguide will be printed using 3D tungsten printing that has improved precision, and reduced roughness. These components will be tested for durability at DIFFER facilities. The performance of the microwave reflectometer, including waveguides, will be tested by using it to analyse the geometry and dynamics of the Magnum PSI plasma beam. The development of sensor-based systems is an important aspect in the integrated research and education program in Electrical Engineering, where DSS is based. The sensing requirements from DIFFER offers an interesting and highly relevant research theme to DSS and exciting projects for engineering students. Hence, this collaboration will strengthen both institutes and the educational offerings at the institute of engineering. Furthermore millimeter wave (mmWave) sensors have a wide range of potential applications, from plasma characterisation (as in this proposal) though to waste separation. Our research will be a step towards realising these broader application areas.
Recente ontwikkelingen op het gebied van microfluïdica en microreactoren maken het mogelijk verschillende laboratoriumtesten te miniaturiseren.Deze zogenaamde “lab-on-a-chip” technologieën maken diagnostische testen buiten het laboratorium (point of care testing) mogelijk.Voor medische testen hoeven artsen geen monsters meer op te sturen naar een gespecialiseerd laboratorium en te wachten op de uitslag, de gegevens kunnen meteen gelezen worden en eventuele therapie direct gestart of daarop aangepast worden. Desondanks loopt de toepassing van de “lab-on-a-chip” technologie in de praktijk achter bij de verwachtingen. De omzetting van idee tot device vergt vaak grote investeringen. Voor het aantonen van de toepasbaarheid van een idee zijn veelal al dure investeringen in productiemiddelen en geconditioneerde ruimten noodzakelijk, terwijl het benodigde geld voor de investeringen alleen verkregen kan worden als kan worden aangetoond dat het idee werkt (“valley of death”). Printtechnologieën kunnen op dat punt een uitkomst bieden. Inkjetprinten, plasmaprinten en 3D-printen zijn relatief eenvoudige, goedkope en flexibele technieken die bijna overal kunnen worden toegepast en ze zijn ook nog eens geschikt voor biologische materialen. In dit project willen we met een combinatie van verschillende printtechnieken (inkjet-, plasma- en 3D printen) een platform genereren waarmee MKBers middels prototypes de haalbaarheid van hun idee met betrekking tot een bio(medische) sensor kunnen aantonen. Door gebruik te maken van een innovatieve detectiemethode, recent ontwikkeld aan de Technische Universiteit Eindhoven, willen we een volledig geprinte sensor produceren die met een smartphone uit te lezen is. We zullen twee praktijkgerichte toepassingen als demonstrator uitwerken. Als eerste een sensor die een ernstige longontsteking van een onschuldige verkoudheid kan onderscheiden, door detectie van het ontstekingseiwit ‘C-reactief eiwit (CRP)’. Als tweede een sensor die snel en eenvoudig de spiegels van een nieuwe oncologische biomarker kan meten en gebruikt kan worden bij de diagnostiek van bepaalde soorten tumoren en het meten van de therapeutische respons.
